1. Field of the Invention
The present invention relates generally to modular I/O electrical assemblies and more particularly to methods and devices for connecting I/O blocks into an I/O cabinet designed for containing a plurality of such blocks making the cabinet suitable for connection into a control system as one element thereof.
2. Description of the Prior Art
The prior art I/O cabinetry had block assemblies mounted therein which depended upon markings on the assemblies to insure a proper assembly of the I/O unit to its matching signal and power source in an I/O block cabinet having one side entry thereto. This caused some units to be damaged when they were connected in an improper sequence. Further, these connections were blind in some I/O modules making this sequencing a matter of guesswork. These blind connections were sometimes impossible when there was nonalignment of the I/O module and the power and signal connectors caused by tolerance buildup during the assembly of the case.
In prior art systems requiring the assembly of individual parts into a system or element of that system a schematic along with an instructional booklet is used. Such a procedure becomes especially burdensome when you begin assembly of electronic control systems such as block I/O cabinetry. These systems first require the assembly of processor blocks and I/O modules into an I/O assembly according to appropriately co-ordinated identical module functions and a further co-ordination of these modules having the same function for identical type of signal input. As an example, identical digital input-output processor blocks for temperature signals could be mismatched with digital input-output I/O modules for line voltage or pressure signals. The result would be at the least an inoperative system.
Similar problems occur in field wiring the processor blocks of I/O modules which can have up to 24 channels which require specific input or output signals co-ordinated to the I/O block which must be not only identified as inputs or outputs but must also be the right type of inputs or outputs as was explained above.
Thus an easily accessible I/O cabinet was needed which would provide easy access and mounting of I/O component modules from both sides of the cabinet and which allowed easy and foolproof assembly of such modules into the cabinet while preventing the application of signal inputs to the I/O modules before power was connected to the modules as well as providing such a sequential connection using a blind fit into an I/O module mounting area in the cabinetry.